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Subjects

Abstract

Silicon is an excellent material for microelectronics and integrated photonics1,2,3, with untapped potential for mid-infrared optics4. Despite broad recognition of the importance of the third dimension5,6, current lithography methods do not allow the fabrication of photonic devices and functional microelements directly inside silicon chips. Even relatively simple curved geometries cannot be realized with techniques like reactive ion etching. Embedded optical elements7, electronic devices and better electronic–photonic integration are lacking8. Here, we demonstrate laser-based fabrication of complex 3D structures deep inside silicon using 1-µm-sized dots and rod-like structures of adjustable length as basic building blocks. The laser-modified Si has an optical index different to that in unmodified parts, enabling the creation of numerous photonic devices. Optionally, these parts can be chemically etched to produce desired 3D shapes. We exemplify a plethora of subsurface—that is, ‘in-chip’—microstructures for microfluidic cooling of chips, vias, micro-electro-mechanical systems, photovoltaic applications and photonic devices that match or surpass corresponding state-of-the-art device performances.

Acknowledgements

This work was supported partially by a European Research Council (ERC) Consolidator Grant ERC-617521 NLL, EU Marie Curie Fellowship 660769 SMILE and TÜBITAK under project 113M930. The authors acknowledge support from the Structural Characterization Facilities at IBC of the HZDR. The authors thank H. Volkan Hünerli for discussions of the chemical procedure.

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Contributions

O.T. and F.Ö.I designed the research and interpreted the results, with help from S.I. Experiments were performed by A.T., O.T., G.M. and Ö.Y. The customized laser was built by I.P. The analytical model was developed by P.E., O.T. and F.Ö.I. Numerical simulations were performed by A.T., O.T. and E.E. Chemical etching was developed by T.Ç., M.Z.B., A.B. and R.T. Material analyses were performed by R.H. and S.I. Waveguide characterization and optical coherence tomography imaging were performed by D.K.K. and S.T., respectively.